Barriers to Entry Are _____,And One Effect of Barriers to Entry

Multiple Choice

Barriers to entry are _____,and one effect of barriers to entry is to _____ the ability of the invisible hand to allocate resources efficiently.

A) uncommon today due to antitrust enforcement;improve
B) forces that limit new firms from joining an industry;reduce
C) forces that limit new firms from joining an industry;irrelevant to
D) uncommon today due to antitrust enforcement;reduce